Facial expression provides sensitive cues about emotional response and plays a critical role in the regulation of interpersonal behavior. Human-observer based methods for measuring facial expression are labor intensive, qualitative, and difficult to standardize across laboratories and over time. To make feasible more rigorous, quantitative measurement of facial expression in diverse applications, the investigators formed an interdisciplinary research group that covers expertise in facial expression analysis and computer vision. In August 1995, the research group received initial funding for Facial Expression Analysis by Computer Image Processing (NIMH #IRO1MH51435). With NIMH support, they created a large representative database for method development and developed and validated a face analysis system that tracks gaze and facial features in digitized image sequences of infant, child, and adult subjects. In near frontal views, the Face Analysis System has achieved concurrent validity with manual FACS coding for 16 of 44 FAGS action units and more than 30 combinations in which they occur. For the competing renewal, the investigators will (1) Increase system robustness to head orientation and head motion (2) Increase the number of recognizable action units to include all 30 of those that have a specific anatomic basis, and (3) Conduct a systematic, large-scale, comprehensive test of the developed Face Analysis System by using multiple databases. These databases encompass subjects of various ages and backgrounds and varying types of emotion induction, head orientation, head motion, size of the face in pixels, and presence of speech. The databases were initially collected to answer substantive questions about emotion processes; they represent the types of data that the Face Analysis System will encounter in psychology research and clinical applications.